Blood and a weapon police believe was used to kill Brittany Killgore were found in the car of a suspect in the marine wife's murder, prosecutors said.

At a plea hearing Thursday, Staff Sgt. Louis Ray Perez, 45, pleaded not guilty to a first degree murder charge in the slaying of the 22 year old who lived in Fallbrook, Calif. Perez was in jail on an unrelated charge of possession of an AR-15 assault rifle at the time of his arrest for murder.

Chilling details of the crime emerged at Perez' hearing: Killgore sent a text message to a friend the night she disappeared that said "help," Deputy District Attorney Patrick Espinoza said.

Killgore, 22, of Fallbrook, Calif., disappeared April 13, after telling friends she was going out in San Diego's Gaslamp Quarter. Her body was found four days later, dumped near Lake Skinner in Riverside County, Calif.

The San Diego County District Attorney's office has not released the manner in which Killgore was killed. They also have not said what type of weapon was found in the car and is believed to be the murder weapon.

Authorities declined to comment on reports that Perez's alleged interest in bondage could have played a factor in Killgore's death.

ABC News' San Diego affiliate found profiles for Perez on two sadomasochism websites where he listed his sexual interests as asphyxiaphilia, electro-torture, rape/victim, and kidnapping, the station said.

Twenty-five-year-old Jessica Lopez, who once lived with Perez, has also been charged with first degree murder in Killgore's death. She entered a not guilty plea in court April 19, and was ordered held on $3 million bail, the San Diego County Sheriff's Department said.

The content of that note has been kept under seal, per judge Kimberlee Lagotta's order, ABC News' San Diego affiliate reported.

Authorities have not commented on the connection between Killgore, Lopez and Perez. Police said they believed Perez was the last person to see Killgore and he became a person of interest shortly after Killgore was reported missing.

The slain woman's grandmother, Cheryl Coble, told the Park Hills Daily Journal in Missouri that Killgore, Perez and an unidentified girlfriend were supposed to go on a dinner cruise the night of April 13, but the girlfriend backed out. Coble said she was unsure if her granddaughter made it to the cruise.

Killgore told friends she was going to spend the evening in San Diego's Gaslamp Quarter. However, authorities said they believed she never made it. Her cell phone was recovered in the area by San Diego trolley security, triggering an investigation.

Killgore filed for a divorce from her husband, Cory Killgore, also 22, just days before she disappeared. Cory Killgore returned from Afghanistan last week following the news of his wife's disappearance.